A newspaper reached out to Bindle asking how many categories they have in the library?
In the previous lesson, our SQL toolbox grew by one more item – DISTINCT
. It allows us to select unique column values or unique combinations in the case of several columns.
This lesson asks a more complex question – we need to count unique values. As we already know we can use the aggregate function COUNT
to count records:
SELECT COUNT(genre) FROM books
This query still returns the total number of books, since we just counted genres for each book.
To count...
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About SQL Habit
Hi, it’s Anatoli, the author of SQL Habit. 
SQL Habit is a course (or, as some of the students say, “business simulator”). It’s based on a story of a fictional startup called Bindle. You’ll play a role of their Data Analyst
and solve real-life challenges from Business, Marketing, and Product Management.
SQL Habit course is made of bite-sized lessons (you’re looking at one atm) and exercises. They always have a real-life setting and detailed explanations. You can immediately apply everything you’ve learned at work. 